Rats which inhaled ethanol vapors for 7 or 14 days underwent a withdrawal syndrome following removal from the inhalation chambers. Approximately sixty percent of rats exposed to the vapors for 3 days also exhibited various withdrawal symptoms but rats exposed to vapors for 24 hours showed no marked withdrawal reaction. In a holeboard test performed approximately 11 hours after removal from the chambers, when blood alcohol concentrations were below the limits of detection, rats exposed to ethanol vapors for 24 hours, 3, 7 or 14 days all had reduced exploratory and locomotor activities. Whether or not this hypoactivity is a manifestation of a withdrawal reaction or reflects some other effect of exposure to ethanol vapors is currently under investigation.